A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science

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PARAMETRIC ANALYSIS OF HUMAN VERTEBRAE TOWARDS VIBRATION IMP ACTS FROM ELECTRIC VEHICLE

STEERING SYSTEM

BY

MUHAMMAD AZRAI BIN AMIR

A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science

(Mechatronics Engineering)

Kulliyyah of Engineering

International Islamic University Malaysia

JANUARY 2017

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i

ABSTRACT

With the importance of reducing carbon footprint and minimizing air pollution, the introduction of electric vehicle (EV) is tipped to be the next best alternative. EV’s feature of zero carbon emission is highly appraised. In effort to improve the EV more advance specifications are installed such as Electric-Powered Assist Steering System (EPAS). The cutting-edge steering system technology is getting popular in automotive industry. It is said and proven to ease and resolve the difficulty that the conventional hydraulic steering system encountered before. The absence of hydraulic system parts such as power steering pump and hydraulic fluid, EPAS gives positive effects for the user with its easy maintenance and lesser weight added to the overall car system.

Although with presence of many advantages of EPAS over hydraulic steering system, it is still prone to induce vibration impacts that affect the driver and passengers. Thus, it exhibit driver`s discomfort and increase fatigue level at low frequency vibration happens. In addition to the bad impact stated before, road condition is also one of the key factors that needed to be taken into consideration. The impact can be felt by the occupant of the vehicle. Low frequency vibration causes stress in the lumbar muscles, where it can lead to discomfort and fatigue around perception threshold towards the person sitting on the vehicle. The negative impacts are worsening during long distance driving. Thus, optimization of vibration is the goal for this research. First method done is data sampling from long distance driving process and repeated laps for short distance driving. Both style of driving are observed for the human vertebrae response towards the vibration. Because of low frequency vibration, data filtration is required to eliminate unwanted trace from the overall signal. Using a few selected model structures such as Autoregressive Models with Exogenous Inputs (ARX), Autoregressive–Moving-Average Model (ARMAX), Box-Jenkins and Output-Error from system modeling and identification technique, the effect of vibration can be minimized. It is proven that modeling using ARX technique with high order output is the best compared to other selected model structures.

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ii

ثحبلا صخلم

،ءاٌٛٙا زٍٛذ ِٓ ذذٌاٚ ْٛتشىٌا خاشاعثٔا ِٓ ذذٌا ح١ّ٘أ عِ

َذمذ جسا١غٌا

( ح١ئاتشٙىٌا ) EV

اٙٔأ ٍٝع ً٠ذثٌا

لأا ٍٟثمرغٌّا

ْٛتشىٌا خاشاعثٔا جض١ِ ًلفض

ح١ئاتشٙىٌا جسا١غٌا ٟفض حِذعٌّٕا ٝمٍذ

إ داش جش١ثو ج

ٚ

ٓ١غذرٌ حٌٚاذِ ٟفض جسا١غٌا

ح١ئاتشٙىٌا ُر٠

ضاِدإ شصوأ خافصاِٛ

اسٛطذ ٗ١جٛرٌا َاظٔ ًصِ

ٌا ذعاغّ

ٌا

ّ صضع

١ئاتشٙو ح١ثعش ٝمٍذ اسٛطذ شصوأ ٗ١جٛذ َاظٔ ح١ٕمذ ا

ياجِ ٟفض جش١ثو حعإص

خاسا١غٌا ذمٌ

ففخ٠ ٗٔأ ذعت اّ١فض دثشٚ ً١ل

ٚ ٠ ًذ

ًواشِ

ٗ١جٛرٌا َاظٔ

ٞذ١ٍمرٌا ٟى١ٌٚسذ١ٌٙا

ًثل ِٓ اٙٙجاٚ ٟرٌا

ٌٚ

با١غ ضعت

َاظٌٕا ءاضجأ

ًصِ ٟى١ٌٚسذ١ٌٙا حخلِ

اٚ ٗ١جٛرٌا َاظٔ

ح١ى١ٌٚسذ١ٌٙا ًئاٛغٌ

ْئفض ، ٗ١جٛرٌا َاظٔ

ٌا ذعاغّ

ٌا

ّ صضع ١ئاتشٙو ا

حٔا١صٌا حٌٛٙع عِ َذخرغٌٍّ ح١تاج٠إ خاش١شأذ ٟطع٠

ًلأ ْصٚٚ

٠ ٌٝإ فال

ٌا

َاعٌا َاظٕ

جسا١غٌٍ

ٚ ِٓ ذ٠ذعٌا دٛجٚ ِٓ ُغشٌا ٍٝع

ا٠اضٌّا ٟفض

ٗ١جٛرٌا َاظٔ

ٌا ذعاغّ

ٌا

ّ صضع ١ئاتشٙو ا

حٔسامِ

ت

ٌا َاظٕ

ٗ١جٛر

حضشع ياض٠ لا ٗٔئفض ،ٟى١ٌٚسذ١ٌٙا ذ١ٌٛرٌ

صاضر٘ا خا

باوشٌاٚ كئاغٌا ٍٝع ششؤذ

ءاٛغٌا ٍٝع ٗٔئفض ،ازى٘ٚ

ذٌٛ١ع حمشِ

ٌٍ

جدا٠صٚ كئاغ ٟفض

ةعرٌا ٜٛرغِ

ذٕع

صاضر٘لاا ٓع حجذإٌا حلفخٌّٕا خاددشرٌا

ٚ ٌٝإ حفضاضلإات

ٌا ش١شأر

ٌا ءٟغ سٛوزٌّا

اٛعٌا ٜذدإ ٟ٘ ك٠شطٌا حٌاد ْئفض ،افٔآ ٓ١عت ا٘زخأ ةج٠ ٞزٌا حغ١ئشٌا ًِ

ساثرعلاا جسا١غٌا ةواس ًثل ِٓ ششلأات طاغدلاا ٓىّ٠ٚ

ةثغرذ صاضر٘لاا

خا

ٌا حلفخِٕ

ددشر ٟفض ٌٝإ ٞدؤذ ْأ ٓىّ٠ اٙٔأ س١د ،شٙظٌا ًفعأ خلالع داٙجإ

حا١ذسلاا َذعت سٛعشٌا ظٍج٠ ٞزٌا صخشٌا ٖاجذ ناسدلإا حثرع يٛد ةعرٌاٚ

ٟفض

جسا١غٌا دادضذٚ

٢ا حٍ٠ٛط خافضاغٌّ جدا١مٌا ءإشأ اءٛع ح١ثٍغٌا ساش ْئفض ،هٌزٌ

ٛ٘ سذثٌا ازٌٙ طاعلأا فذٌٙا ٓ١غذذ

ٜٛرغِ

ٌٝٚلأا حم٠شطٌا صاضر٘لاا

حٍّعرغٌّا

٘

ٟ حٍ٠ٛط خافضاغٌّ جدا١مٌا ح١ٍّع ِٓ خأا١ثٌا خإ١ع زخأ خافٌٚ

جش١صل خافضاغٌّ جسشىرِ

ًعفض جدس حظدلاِ ُذ ذمٌٚ

ٛذٔ ْاغٔلإا خاشمفض

صاضر٘لاا

ٟفض و لا طّٔ

ٟ ،ضفخٌّٕا ددشرٌا صاضر٘ا ةثغت جدا١مٌا ذ ْئفض

خ١شش

ٌا خأا١ث بٍٛطِ

ٍٝع ءالمٌٍ

ٞأ ٗ١فض بٛغشِ ش١غ ششأ ح١ٌاّجلإا جساشلإا ٍٝع

ا ِٓ ً١ٍل دذع َاذخرعات قشطٌ

ٌا جرّٕٛ

ح١

ٌا ذازٌا ساذذٔلاا ضرأّ ًصِ جسارخّ

ٟ عِ

خلاخذِ

( ح١جساخ

،) ARX

ٚ ضرّٛٔ

ا يذعِ

ا ساذذٔلا

ٟذازٌ

نشذرٌّا

( ARMAX ،)

ضرّٛٔٚ

ظوٛت –

،ضٕىٕج أطخٌا خاجشخِٚ

ِٓ

َاظٔ

حجزٌّٕا

،

ح١ٕمذٚ

،ذ٠ذذرٌا ش١شأذ ً١ٍمذ ْاىِلإاثفض

صاضر٘لاا

دثش

ْأ حجزٌّٕا

َاذخرعات ح١ٕمذ

عِ ARX خاجشخٌّا

حجسذٌا ِٓ

ٟ٘ ا١ٍعٌا ًلفضلأا

ِ حٔسام

ٌا قشطٌات

ٕ

ّٛ

جر ح١

ٌا ٜشخلأا

جسارخّ

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iii

APPROVAL PAGE

I certify that I have supervised and read this study and that in my opinion; it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Master of Science (Mechatronics Engineering)

……….……….

Siti Fauziah binti Toha Supervisor

I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Master of Science (Mechatronics Engineering)

……….……….

Salmiah Binti Ahmad Internal Examiner

……….……….

Abdul Halim Embong Internal Examiner

This dissertation was submitted to the Department of Mechatronics Engineering and is accepted as a partial fulﬁlment of the requirements for the degree of Master of Science (Mechatronics Engineering)

……….………

Tanveer Saleh Head, Department of Mechatronics

This dissertation was submitted to the Kulliyyah of Engineering and is accepted as a partial fulﬁlment of the requirements for the degree of Master of Science (Mechatronics Engineering)

……….……….

Erry Yulian Triblas Adesta Dean, Kulliyyah of Engineering

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DECLARATION

I hereby declare that this dissertation is the result of my own investigations, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institutions.

Muhammad Azrai bin Amir

Signature ……… Date ……….

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INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH

PARAMETRIC ANALYSIS OF HUMAN VERTEBRAE TOWARDS VIBRATION IMPACTS FOR ELECTRIC VEHICLE

STEERING SYSTEM

I declare that the copyright holders of this dissertation are jointly owned by student and IIUM.

No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below.

1. Any material contained in or derived from this unpublished research may only be used by others in their writing with due acknowledgement.

2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purposes.

3. The IIUM library will have the right to make, store in a retrieval system and supply copies of this unpublished research if requested by other universities and research libraries.

By signing this form, I acknowledged that I have read and understand the IIUM Intellectual Property Right and Commercialization policy

Affirmed by Muhammad Azrai bin Amir.

……… ………

Signature Date

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vi

ACKNOWLEDGEMENTS

In the name of Allah, the most Gracious, the most Merciful. Praise be to the Almighty Allah, with His mercy and blessings that have been granted to the author. Peace be upon His messenger Muhammad S.A.W, his families and companions.

I express heartfelt gratitude to my project supervisor Dr. Siti Fauziah Toha. I owe more than I can articulate to her. I thank her for her invaluable support, encouragement and guidance during my years at the Biomechatronics Laboratory, Department of Mechatronics, International Islamic University Malaysia. I genuinely appreciate the many hours she has spent working with me on this thesis as well as the research work. Her friendly approach and unbound patience have left a deep impression upon me. My gratitude to Prof. Ishak Aris from Universiti Putra Malaysia (UPM) as my field supervisor. His ideas and suggestions were incredible and really helped me in all my research works.

I will be forever grateful to my fellow research friends who have been so gracious.

Mohd. Hafiz, Mohd Fakhruddin, Rozaidi, Amirul, Zakariya, Tengku Afif, Hafiz Zakaria, Rabiatul and Tuan Shazana. Thank you all for providing inspiration and helpful suggestions as well as many hours of discussion on the thesis work. I am also indebted to my research group for your continuous encouragements. My special thanks also go to Dr. Hazlina, Dr. Shahrul Naim, Dr. Mahbubur and Dr. Nahrul for all the teachings and guidance during my research years. To the senior technician staffs, Mr. Nasrul and Mr Shahlan for the help of maintaining the hardware for my research and laboratory facilities, as well as to the Research Management Centre (RMC), IIUM for guiding me on purchasing the hardware device that is the key for the research.

Finally, I would like to express my deepest love and appreciation to my family members who has been an incredible support and provided the never-give-up spirit.

Thank you all for all your sacrifices and helps throughout the ups and downs in my life.

I would also like to acknowledge the research grant from the Ministry of Higher Education (MoHE) in Malaysia, and for my financial assistance from MyBrain15 scholarship that really helped me in education expense throughout my study.

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CHAPTER 2: LITERATURE REVIEW ... 12

2.1 Whole-Body Vibration (WBV) ... 12

2.1.1 Definition of Vibration ... 12

2.1.1.1 Frequency ... 14

2.1.1.2 Amplitude ... 14

2.1.1.3 Acceleration (Measure of Vibration Intensity) ... 14

2.1.2 Standard of Measurement of Vibration ... 15

2.1.3 Vibration Threshold Limit on Whole Body ... 16

2.1.4 Vibration Measurement Device ... 18

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2.2 Whole-Body Vibration and Human Vertebrae Relationship ... 19

2.2.1 Human Musculoskeletal Anatomy ... 19

2.2.1.1 Lumbar Vertebrae ... 19

2.2.1.2 Lumbar Muscles ... 21

2.2.2 Exposure to Whole Body Vibration ... 23

2.2.3 Health Effects of Whole-Body Vibration ... 27

2.2.3.1 Physical Effects ... 27

2.2.3.2 Psychological Effects ... 29

2.2.4 Electromyography (EMG) Signals ... 30

2.2.4.1 Definition of EMG ... 30

2.2.4.2 Whole-Body Vibration and EMG ... 31

2.2.4.3 EMG Measurement Device ... 32

2.3 Mechanical Vibration in Vehicles ... 33

2.3.1 Noise, Vibration, Harshness (NVH) ... 33

2.3.2 Vehicle Suspension System Comparison ... 34

2.3.3 Electric-Powered Assist Steering System (EPAS) ... 36

2.3.3.1 Definition of EPAS ... 37

2.3.3.2 Components of EPAS ... 37

2.3.3.3 Comparison between EPAS and Conventional Hydraulic Steering System ... 39

2.3.3.4 Matters to be concerned about EPAS ... 41

2.3.4 Elevation and Road Profile ... 43

2.4 Signal Filtration ... 44

2.4.1 Vibration Threshold Limit ... 44

2.4.2 Data Filter ... 45

2.4.2.1 Butterworth Filter ... 45

2.4.2.2 Chebyshev Filter ... 46

2.4.2.3 Choosing a Suitable Filter ... 48

2.5 System Modeling and Identification ... 48

2.5.1 Model Structures ... 48

2.5.1.1 Autoregressive Exogenous Model (ARX) ... 50

2.5.1.2 Autoregressive–Moving-Average Model with Exogenous Inputs Model (ARMAX) ... 51

2.5.1.3 Box-Jenkins Model (BJ) ... 52

2.5.1.4 Output-Error Model (OE) ... 53

2.5.2 Comparison between Models ... 53

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ix

2.6 Summary ... 54

CHAPTER 3: EXPERIMENTATION OF HUMAN VERTEBRAE RESPONSES TOWARDS STEERING VIBRATION ... 56

3.1 Introduction ... 56

3.2 Classification of Elements in the Experiment ... 56

3.2.1 Input Acceleration ... 56

3.2.2 Output Muscle Signal ... 57

3.2.3 Input and Output Data Relationship ... 57

3.2.4 Experiment Flowchart ... 57

3.2.5 Ideal Human Subject Conditions ... 58

3.2.6 Questionnaires ... 59

3.2.7 Data Sampling ... 59

3.3 Measurement Devices ... 60

3.3.1 Input Measurement Device ... 60

3.3.1.1 Calibration of Input Device ... 60

3.3.2 Output Measurement Device ... 61

3.3.3 Elevation Measurement Device ... 62

3.4 Experiment #1: IIUM Gombak – Penang ... 62

3.4.1 Road Profile ... 62

3.4.2 Experimental Setup & Results ... 63

A. Result of Experiment: Input Acceleration ... 65

B. Result of Experiment: Output Muscle Signal ... 66

3.5 Experiment #2: Batu Caves – Ulu Yam ... 67

3.5.2 Experimental Setup ... 69

3.5.3 Results ... 70

3.6 Experiment #3: Batu Caves – Bentong ... 73

3.7 Experiment #4: IIUM Roundabout ... 78

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3.8 Summary ... 84

CHAPTER 4: DATA ANALYSIS FROM ALL EXPERIMENTS ... 85

4.1 Data Filtration ... 85

4.1.1 Filter Order ... 85

4.2 System Modeling and Identification Technique ... 86

4.3 Experiment #1: IIUM Gombak – Penang ... 86

4.3.1 Data Filtration ... 86

4.3.2 System Modeling and Identification Process ... 88

4.4 Experiment #2: Batu Caves – Ulu Yam ... 90

A. Human Subject 1 ... 90

B. Human Subject 2 ... 91

4.5 Experiment #3: Batu Caves – Bentong ... 95

4.6 Experiment #4: IIUM Roundabout ... 100

C. Human Subject 3 ... 103

D. Human Subject 4 ... 103

E. Human Subject 5 ... 104

F. Human Subject 6 ... 104

G. Human Subject 7 ... 105

H. Human Subject 8 ... 105

4.6.2 System Modeling and Identification ... 106

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xi

C. Human Subject 3 ... 109

D. Human Subject 4 ... 110

E. Human Subject 5 ... 112

F. Human Subject 6 ... 113

G. Human Subject 7 ... 115

H. Human Subject 8 ... 116

CHAPTER 5: COMPARATIVE ASSESSMENTS ... 119

CHAPTER 6: CONCLUSION AND RECOMMENDATION ... 125

6.1 Conclusion ... 125

6.2 Recommendation & Future Work ... 126

6.2.1 Ant Colony Optimization ... 127

6.2.2 Artificial Immune System ... 127

REFERENCES ... 129

LIST OF PUBLICATION: PUBLISHED JOURNAL PAPER ... 137

APPENDIX I: HUMAN SUBJECT INFORMATION DETAILS ... 143

APPENDIX II: QUESTIONNAIRES FORM ... 144

APPENDIX III: CONSENT FORM ... 146

APPENDIX IV (A): DEVICE MANUAL (LARSON DAVIS HVM100 VIBRATION MONITOR AND SEAT PAD ACCELEROMETER) ... 151

APPENDIX IV (B): DEVICE MANUAL (GTEC GMOBILAB+) ... 153

APPENDIX V: APPROVAL LETTER TO CONDUCT EXPERIMENTS FROM IIUM RESEARCH ETHICS COMMITTEE (IREC) ... 155

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LIST OF TABLES

Table No. Page No.

2.1 Levels of Comfort for Vibration Environments 17 2.2 Details of Back Muscles of Human Vertebrae 22 2.3 Exposure Limit of Vibration towards Hand-Arm and

Whole-body

24 2.4 Guideline of Whole-body Vibration Exposure 25 2.5 Examples of Occupational Vibration Exposure 26 2.6 Relevant Frequency Changes for Vibration Exposure 29 2.7 Comparison between Passive and Active Suspension

System

35

2.8 Electric Components in EPAS 38

3.1 Ideal Range of Human Subject 58

3.2 Calibration Data of HVM100 60

3.3 Experiment IIUM – PENANG: Details of (a) HVM100 and (b) gTec

64 3.4 Experiment BATU CAVES – ULU YAM: Details of (a)

HVM100 and (b) gTec

70 3.5 Experiment BATU CAVES – BENTONG: Details of (a)

HVM100 and (b) gTec

75 3.6 Experiment IIUM ROUNDABOUT: Details of (a)

HVM100 and (b) gTec

80

4.1 Details of the Experiment IIUM - Penang 86

4.2 Experiment IIUM – PENANG: Comparison of Selected Model Structures

88

4.3 Details of the Experiment Batu Caves – Ulu Yam 90

4.4 Comparison of Selected Model Structures – Human Subject 1

92 4.5 Comparison of Selected Model Structures – Human

Subject 2

94 4.6 Details of the Experiment Batu Caves - Bentong 95

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4.7 Comparison of Selected Model Structures – Human Subject 1

Subject 2

99 4.9 Details of the Experiment IIUM Roundabout 101 4.10 Comparison of Selected Model Structures – Human

Subject 1

Subject 2

Subject 3

Subject 4

Subject 5

Subject 6

Subject 7

Subject 8

116 5.1 Percentage Accuracy for Parametric Modelling of the

System

119 5.2 RMS Value of All Experiments in 3 Axes 121

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xiv

LIST OF FIGURES

Figure No. Page No.

1.1 Flowchart of the Research 8

2.1 Representation of the Measures of Vibration Exposure 13 2.2 Measurement Axes of Whole-body Vibration in the Human

Body

15 2.3 Frequency, Acceleration Amplitude and Exposure Time:

(a) x-axis and y-axis, (b) z-axis

17 2.4 Vibration Measurement Device: (a) the position of seat pad

accelerometer and (b) the components of vibration measurement device

18

2.5 (a) Diagram of Human Vertebrae, (b) Horizontal Simplified Illustration of Lumbar Vertebrae using Spring- Damper System

20

2.6 Position of Lumbar Muscles 22

2.7 Monitoring Electromyography (Muscle Signals) 30 2.8 Placement of Electrodes on the Human Lumbar Muscles 32 2.9 EMG Monitoring and Recording via gTec gMobilab+

Software: (a) at rest and (b) muscle reaction on excitation of certain level of vibration

33

2.10 Illustration of Noise, Vibration and Harshness in the Vehicle

34 2.11 (a) Passive Suspension System and (b) Active Suspension

System

36

2.12 Example of an EPAS 39

2.13 (a) Hydraulic Steering System, (b) Electric-Powered Assist Steering System and (c) Hardware Structure of EPAS

40

2.14 Block Diagram of a Close-Loop System 45

2.15 Comparison between Butterworth and Chebyshev Filters 47 2.16 Algorithm for Modeling and System Identification 49

2.17 ARX Structure Model 51

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2.18 ARMAX Structure Model 52

2.19 Box-Jenkins Structure Model 53

2.20 Output-Error Structure Model 53

2.21 Steps to Determine Model Structure and Order 54

3.1 Block Diagram of the Experiment 57

3.2 Flowchart of the Experiment 58

3.3 Calibrating Device using Sensitivity Data 61

3.4 IIUM Gombak to Penang: (a) Route on Map, and (b) Elevation Profile

63 3.5 Power Spectral Density of Vibration via HVM100: (a)

Manually Calculated Fs and (b) PSD Generator

65 3.6 Acceleration from Vibration during the Experiment 65

3.7 Graph of Acceleration vs Time 66

3.8 Power Spectral Density of Lumbar Muscle via gTec: (a) Manually Calculated Fs and (b) PSD Generator

66

3.9 EMG Signal vs Time Graph 67

3.10 Route from Batu Caves to Ulu Yam: (a) Route on Map, and (b) Elevation Profile

68 3.11 (a) Human Subject Seats on the Seat Pad Accelerometer,

(b) The Position of Seat Pad Accelerometer, (c) The Position of End-to-end Electrode Patches and (d) The Position of Ground at the Elbow

69

3.12 Power Spectral Density of Vibration via HVM100: (a) Manually Calculated Fs and (b) PSD Generator

71 3.13 Acceleration from Vibration during the Experiment 71 3.14 Time Domain of Input of the Experiment 72 3.15 Power Spectral Density of Lumbar Muscle via gTec: (a)

73 3.16 Route from Batu Caves to Bentong: (a) Route on Map, and

(b) Elevation Profile

76 3.18 Acceleration from Vibration during the Experiment 77

3.19 Acceleration vs Time Graph 77

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77

3.22 Route of IIUM roundabout: (a) Route on Map, and (b) Elevation Profile

82

3.24 Acceleration vs Time Graph 82

83

4.1 Comparison between Filter Order at 0.5 Hz cut-off frequency: (a) 2nd Order and (b) 20th Order

85 4.2 Comparison of Raw (red) and Filtered (green) Data of

Human Subject 1: (a) Input and (b) Output

87

4.3 Block Diagram of New Plant (Open Loop) 89

4.4 New Output Muscle Signal (green) compared with Old (red)

Human Subject 1: (a) Input Acceleration and (b) Output Muscle Signal

91

4.6 Comparison of Raw (red) and Filtered (green) Data of Human Subject 2: (a) Input Acceleration and (b) Output Muscle Signal

92

93

96

97

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xvii

4.13 Block Diagram of New Plant (Open Loop) 98 4.14 New Output (green) compared with Old (red) 99 4.15 Block Diagram of New Plant (Open Loop) 100 4.16 New Output Muscle Signal (green) compared with Old

(red)

102

103

104

105

4.25 Block Diagram of New Plant (Open Loop) 106 4.26 New Output Muscle Signal (green) compared with Old

(red)

107 4.27 Block Diagram of New Plant (Open Loop) 108 4.28 New Output Muscle Signal (green) compared with Old

(red)

108 4.29 Block Diagram of New Plant (Open Loop) 109

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xviii

(red)

117 5.1 RMS Values of Tri-axial Vibration from IIUM – Penang

Experiment

123 5.2 RMS Values of Tri-axial Vibration from Batu Caves – Ulu

Yam Experiment

123 5.3 RMS Values of Tri-axial Vibration from Batu Caves –

Bentong Experiment

124 5.4 RMS Values of Tri-axial Vibration from IIUM

Roundabout Experiment

124

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xix

LIST OF ABBREVIATIONS

ACO Ant Colony

Optimization

IPCER International Postgraduate Conference Engineering Research

AIS Artificial Immune

System

ISO International Standard Organization

ANSI American National

Standard Institute

MoHE Ministry of Higher Education

APERC Asia Pacific Energy Research Centre

MiL Model in Loop

ARMAX Autoregressive-

Moving-Average Model with Exogenous Input

n.d. No date

ARPN Asian Research

Publishing Network

NVH Noise, Vibration, Harshness

ARX Autoregressive

Exogenous

OE Output-Error

AS Ant System PC Personal Computer

BJ Box-Jenkins Ph. D. Doctorate of Philosophy

BW Bandwidth PLUS Projek Lebuhraya Utara-

Selatan

DATAQ Data Acquisition PPV Peak Particle Velocities

ECU Electronic Control

Unit

PSD Power Spectral Density

EMG Electromyography RAM Random Access Memory

EPAS Electric Power Assist Steering System

RMC Research Management

Centre

et al. (et alia): and others RMS Root Mean Square

EU European Union SID System Identification

EV Electric Vehicles UPM Universiti Putra Malaysia

HS Human Subject WBW Whole-Body Vibration

HVAC Heating, Ventilating, Air-Conditioning

3D Three Dimension

i.e. (id est): that is IIUM International Islamic

University Malaysia

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LIST OF SYMBOLS

a acceleration kg kilogram

bin Binary Format File km kilometer

cc cubic centimeter m (unit) meter

cos cosine function m mass

d Distance m/s Meter-per-Second

D(s) Disturbance m/s² Meter-per-Second-

Squared

dB Decibel R(s) input

F Force s second

Fs Sampling Frequency t time

Gb GigaByte Ts Sampling time

GHz GigaHertz V_AC Alternate-current voltage

H height xlsx Microsoft Excel Format

File

Hz Hertz Y(s) output

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CHAPTER 1 INTRODUCTION

1.1 BACKGROUND OF STUDY

As the world advances, the technology is also going a step forward, in every field. In transportation, people have benefited from the usage of vehicles to get them to other places easily and in a quick time. For example, we are driving a car to go north from Kuala Lumpur to Penang in just 4 hours, or we are on the airplane when we travel 18228.9 km from Singapore to Bangkok for just 3 hours. These proved the advantages of the advancement in vehicle technology have modernized our way of locomotion.

Electric vehicles (EVs) are seen by many as a potential way to improve the environmental aspects of road transport. Most notably, they could play an important role in reducing road transport related carbon emissions (Thiel et al, 2012). With Malaysia’s aspiration to achieve 20% EV usage by the year 2020 (APERC, 2013), plans to have more charging stations have progressively started in Putrajaya and Kuala Lumpur (Mohd. Shahar, F., 2013). The demand to include more functions for active safety and comfort systems in EV have increased and one of them is electric power assist steering system (EPAS). Conventional hydraulic steering system cannot meet this new demand due to the control unit’s pure hydro-mechanical and complex solution (M. K. Hassan et al, 2012; R. Murugan et al, 2008). Thus, EPAS are currently replacing hydraulic steering system due to steering feel tenability, modularity and environmental compatibility. Although EPAS has been proven to have a positive effect on overall vehicle safety, reports have shown that EPAS causes driver’s

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discomfort from vibrations at low magnitude around perception threshold. Such low- frequency movements produce motion sickness with direct impact to the driver’s spinal vertebrae (Auberlet et al, 2012).

Whole-body vibrations occur when the human body is in contact with a vibrating surface. Oscillations in the frequency range from 1 to 80 Hz are called vibrations in existing standards (Wu, X. & Rakheja, S., 2009). For higher frequencies, the human body becomes less sensitive. Movements with frequencies below 1Hz are denoted as motions and the excitation with such low-frequency movements produce motion sickness (Sueki et al, 2009). The effects of vibrations on human spinal from hydraulic steering system were investigated to be a bit higher than the perception level, which causes stress and sickness on the human body (Dariusz, 2011; Xin L et al, 2009). However, there is a limited number of the study on the relationship of vehicle steering vibration impact towards human vertebrae conducted using EPAS system since more researchers are focusing on energy optimization strategy in the electric vehicle. Therefore, thorough investigations on human vertebrae response to vibration become more important. As the quality of life becomes more important, not only the driver’s health aspect is important components of the acceptability of a vehicle, but also the level of tolerance discomfort caused by seat and steering also plays a crucial role.

One of the people who are in a part of transportation, specifically the car, is the driver, who maneuvers the automobile and takes the responsibility to drive the vehicle safely and carefully. This research will focus and study the impact of vibration produced from the steering to the driver where impact towards other passenger is neglected. When the driver is uncomfortable, fatigue will eventually occur. Fatigue is

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one of the main factors that can reduce the performance of the driving. Fatigue can be measured when someone is not 100-percent capable to focus on doing task. And such, decreasing in driving performance is said to be one of the causes of road accidents.

“Road safety is not about having smooth roads and the most advanced vehicles but involves many factors” (Wong, S. V., 2014)

Wong S. W. (2014) also emphasized the factors including the driver, as well as the circumstances before driving play a role in road safety. Becoming fatigue can be triggered by many factors, especially the health condition of the driver himself and also the condition of the vehicle he is driving. Sleepiness can also be considered one of the fatigues, as the driver has not fully capable in car driving and handling. A comfortable car means comfortable driving.

According to De Silva (1999), unwanted vibration can cause fatigue or degrade the performance of a structure. Therefore, it is a must for the engineer to eliminate and reduce vibration and the effects of vibration.

The benefit of better information and knowledge about the perception of vibrations and the human response to vibrations allows improving the EPAS and seat design so that comfort would increase and the annoyance experienced from excessive vibrations would be reduced. Therefore, the needs for an investigation on the perception of these combined complex stimuli in the range of human perception thresholds and comfort to evaluate the effects of EPAS system on the human vertebrae is crucial. Many of the modeling approaches before have come out with mathematical equations which assumptions made that restrict the actual performance of the vehicular vibration impact (Chunhua, H., 2008; Huaiquan, Z. & Shuanyong, C., 2011). Therefore, an extensive fundamental research on novel modeling technique to

A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science

PARAMETRIC ANALYSIS OF HUMAN VERTEBRAE TOWARDS VIBRATION IMP ACTS FROM ELECTRIC VEHICLE

عِ ARX خاجشخٌّا

DECLARATION

INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

ACKNOWLEDGEMENTS

TABLE OF CONTENTS

CHAPTER 2: LITERATURE REVIEW ... 12

CHAPTER 3: EXPERIMENTATION OF HUMAN VERTEBRAE RESPONSES TOWARDS STEERING VIBRATION ... 56

CHAPTER 4: DATA ANALYSIS FROM ALL EXPERIMENTS ... 85

CHAPTER 5: COMPARATIVE ASSESSMENTS ... 119

LIST OF PUBLICATION: PUBLISHED JOURNAL PAPER ... 137

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATIONS

LIST OF SYMBOLS

CHAPTER 1 INTRODUCTION